In-vehicle systems that estimate shapes of roads on which the vehicles are running, to control steering of the vehicles, and/or warn of risks of collision of vehicles according to the shapes of the roads, have been developed to date. In the in-vehicle systems as described above, shapes of roads need to be accurately estimated in order to appropriately control the vehicles. Such an apparatus for estimating a shape of a road is disclosed in, for example, Patent Literature 1.
An in-vehicle road shape identification apparatus disclosed in Patent Literature 1 detects a position and shape of a roadside stationary object such as a guard rail, based on a plurality of detected points which are obtained by a radio wave radar. Specifically, the in-vehicle road shape identification apparatus extracts a group of detected points which are formed by adjacent detected points, from the plurality of detected points which are obtained by the radio wave radar, and detects the group of detected points as the roadside stationary object such as a guard rail. In general, the roadside stationary object such as a guard rail is positioned along a road on which the vehicle runs and has a shape similar to that of the road. Therefore, the in-vehicle road shape identification apparatus is allowed to estimate and calculate the shape of the road based on the shape of the group of detected points representing the roadside stationary object, such as s guard rail, as detected in the above-described manner.